Yes. I had read all the books first. I always saw Jackson Lamb as a cross between James Bond & Jim Royle and Gary Oldman has so nailed it. Believe he had read the books as well and so wanted the role.I think having read the books first or at least one, helps massively with Slow Horses, as you already have a mental picture of the characters, which the series has managed to cast exceptionally well ( imo )